• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Quantum Chemical Study of Supercritical Carbon Dioxide Effects on Combustion Kinetics
【24h】

Quantum Chemical Study of Supercritical Carbon Dioxide Effects on Combustion Kinetics

机译：燃烧动力学超临界二氧化碳作用的量子化学研究

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In oxy-fuel combustion, the pure oxygen (O-2), diluted with CO2 is used as oxidant instead air. Hence, the combustion products (CO2 and H2O) are free from pollution by nitrogen oxides. Moreover, high pressures result in the near liquid density of CO2 at supercritical state (sCO(2)). Unfortunately, the effects of sCO(2) on the combustion kinetics are far from being understood. To assist in this understanding, in this work we are using quantum chemistry methods. Here we investigate potential energy surfaces of important combustion reactions in the presence of the carbon dioxide molecule. All transition states and reactant and product complexes are reported for three reactions: H2CO + HO2 -> HCO + H2O2 (R1), 2HO(2) -> H2O2 + O-2 (R2), and CO + OH -> CO2 + H (R3). In reaction R3, covalent binding of CO2 to the OH radical and then the CO molecule opens a new pathway, including hydrogen transfer from oxygen to carbon atoms followed by CH bond dissociation. Compared to the bimolecular OH + CO mechanism, this pathway reduces the activation barrier by 5 kcal/mol and is expected to accelerate the reaction. In the case of hydroperoxyl self-reaction 2HO(2) -> H2O2 + O-2 the intermediates, containing covalent bonds to CO2 are found not to be competitive. However, the spectator CO2 molecule can stabilize the cyclic transition state and lower the barrier by 3 kcal/mol. Formation of covalent intermediates is also discovered in the H2CO + HO2 -> HCO + H2O2 reaction, but these species lead to substantially higher activation barriers, which makes them unlikely to play a role in hydrogen transfer kinetics. The van der Waals complexation with carbon dioxide also stabilizes the transition state and reduces the reaction barrier. These results indicate that the CO2 environment is likely to have a catalytic effect on combustion reactions, which needs to be included in kinetic combustion mechanisms in supercritical CO2.
机译：在氧燃料燃烧中，用CO2稀释的纯氧（O-2）用作氧化剂而不是空气。因此，燃烧产物（CO 2和H 2 O）不受氮氧化物的污染。此外，高压导致超临界状态下CO2的接近液体密度（SCO（2））。不幸的是，SCO（2）对燃烧动力学的影响远远不明显。为了协助这种理解，在这项工作中，我们正在使用量子化学方法。在这里，我们研究了在二氧化碳分子存在下重要燃烧反应的潜在能量表面。报告所有过渡状态和反应物和产品配合物的三种反应：H 2 CO + HO2 - > HCO + H 2 O 2（R1），2HO（2） - > H 2 O 2 + O-2（R2），CO + OH - > CO 2 + H. （r3）。在反应R3中，CO 2与OH基团的共价结合，然后CO分子打开新的途径，包括从氧转移到碳原子的氢转移，然后是CH键解离子。与双分子OH + CO机理相比，该途径将活化屏障减小5千卡/摩尔，预计将加速反应。在氢过氧基自反应2HO（2） - > H 2 O 2 + O-2的情况下，发现含有与CO2的共价键的中间体不具有竞争力。然而，观众CO2分子可以稳定循环过渡状态并通过3kcal / mol降低屏障。在H 2CO + HO2 - HCO + H 2 O 2反应中也发现了共价中间体的形成，但这些物种导致基本上更高的活化屏障，这使得它们不太可能在氢转移动力学中发挥作用。用二氧化碳van der Wa种络合也稳定过渡状态并降低反应屏障。这些结果表明，CO 2环境可能对燃烧反应具有催化作用，这需要包括在超临界CO2中的动力学燃烧机制中。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号